top of page

The Rotary Dial Telephone 

The first phones had no dial. With switchboards staffed by operators, dials were not needed. But automated systems required something like a dial to enable numbers to be sent to the exchange. The first practical rotary dial was invented in 1898 (US patent No. 597,062). This was by the prolific Alexander Keith and the Erickson brothers. Some credit Almon Strowger (US patent 486,909) with the first dial. However, his version needed 5 wires from the telephone to the central office so was not practical and little used compared to Keith's dial. 

 

Over the next ~25 years the dial continued to be improved with the "numbers plus letters" dial introduced in New York City in 1922. See Note below.

 

Dialing causes the line current to be interrupted (e.g., 5 pulses for the digit 5). These pulses are then counted by exchange relays or other recording methods. With a dial, no operator was needed for local calls.

early rotary dial phone from London Science Museum

Rotary dial, circa 1900. This dial was circular like the fully mature dial but instead of holes, it had lugs on a finger plate for the user to grab and rotate. 

This model is from the Science Museum of London, UK. 

Candlestick phone from 1920's

The “Candlestick” phone, featuring a dial with numbers and letters, was introduced in the early 1920s

From 1930 to about 1940 the type-D handset was popular

From 1930 to about 1940 the
type-D handset was popular.

100’s of millions of dial phones were made.
 

Touch Tone dials (keypad) began replacing the pulse dial in 1963.

Source: Paul-F

Since Alexander Graham Bell's time, thousands of telephone varieties have emerged.  Some are pedestrian designs while others are exotic. Since about 2014, AI generated art has been available. Imagine if Leonardo Da Vinci created a dial telephone, how might it look? 

 

Here are few examples of phone designs created by the DALL-E 2 generative art service. There are many sites devoted to vintage telephones.  The coverage here is the very tip of the iceberg. See the excellent Telephone Collectors International (TCI) site; www.telephonecollectors.org for a wealth of resources. 

Notes: 

 

For a deeper dive, see "Early Work on Dial Telephone Systems" by R.B. Hill, Bell Laboratories Record, Jan 1953, page 22. 

 

Also, see article below on Francis Blake. His transmitter invention was essential for Bell's success. 

Francis Blake: An Unsung Hero?

(This article was originally published by the Microwave Journal, November, 2023, author Eric Higham.)
 

The Time Travel feature highlights the early pioneers that have helped shape the trajectory of the electronics industry. Since we started this feature, we have profiled Max Planck, Nikola Tesla, Guglielmo Marconi, James Clerk Maxwell, Hedy Lamarr and Oliver Heaviside, all recognizable names. As I started thinking about the November profile, I saw that Francis Blake was granted a U.S. patent in November 1881 for the “Speaking Telephone” and thought “who?”

It turns out that Francis Blake (1850-1913) was born in Newton, Mass., less than 10 miles up the road from the Microwave Journal Offices. He began working as a scientist with the U.S. Coast Survey at 15. In 1874, Blake married into a very wealthy family, allowing him to leave his job and pursue his passions as an inventor and later, a photographer.

Francis Blake inventor of "Blake Transmitter"

This is where the story gets interesting for the electronics community. Alexander Graham Bell received a U.S. patent for the telephone in 1876, but by most accounts, the business he started was struggling. Bell’s telephone received calls, but it did not transmit them very well or very loudly. At the time, Western Union was Bell’s main competitor, and they were using a carbon-based transmitter from Thomas Edison that performed much better.

When Blake learned of the telephone patent, he began experimenting to improve the quality of the transmitter. For the next two years, he worked with Bell employees to refine the design to correct a whole host of resonance, mounting, contact point and material issues. In 1878, satisfied that he had a viable improvement, Blake took his transmitter to the Bell offices and after thorough testing by Thomas Watson, the person who received Bell’s first phone call, the Bell Company bought Blake’s design.

Early Telephone with Blake Transmitter

Early Telephone with Blake Transmitter on the left
London Science Museum

Feeling confident that they had a transmitter that was as good as or better than what Edison had developed for Western Union, the Bell Company sued Western Union for patent infringement and won. Western Union settled out of court and surrendered all its patents and telephone business to the smaller Bell Company. From these beginnings and armed with the patent and the “Blake Transmitter,” as it became known, the Bell Company grew into Bell Telephone, a behemoth that had revenues of more than $400 billion with more than one million employees before it was broken up in the early 1980s.
 

The proceeds from the sales and licensing of the Blake Transmitter made Francis Blake independently wealthy. In 1884 he took up photography and it quickly became a passion. In 1885, Blake purchased an instantaneous shutter camera, which meant a shutter speed of about 1/300th of a second. Not satisfied, Blake designed a focal plane shutter that allowed shutter speeds of 1/1000th -1/2000th of a second. This allowed stop-action photographs of moving objects that were quite different from what was common at the time.
 

Francis Blake was a bit of a Renaissance person with his interests and inventions. He rubbed shoulders with the people credited with developing the U.S. phone industry, but he did not have that notoriety. His Blake Transmitter was widely used for 20 years after it was patented, and it was credited with speeding up the development and deployment of telephony in the U.S. So, the answer to my question of “who?” is a man who may be the unsung hero of an industry that is currently approaching $2 trillion in revenues.  (END)

There were many inventors working feverishly on improved microphone transmitters in the early years.  Bell's first microphone was deficient in many ways so he and Watson were on the hunt for an improved version.

The development history is somewhat confusing with claims and counter-claims over who invented the "transmitter" with its many versions. One thing is sure, Blake had an important role and his version became the favorite of the Bell company.

Blake Transmitters dominated telephony from 1878 to about 1890, with many still in use long after. See
https://ethw.org/Telephones#Variable_Resistance_Transmitters for more details. 

Below is an image (1880-1900) from the London Science Museum. On the right side of the telephone is a Blake carbon button microphone. 

bottom of page